In 1870, an Illinois representative introduced to the House of Representatives a bill to declare several days federal holidays. The bill's language was approved by the House and the Senate, and signed into law by President Ulysses S. Grant in late June 1870. It included Jan. 1, July 4, Thanksgiving Day and Dec. 25 as holidays. Congress acknowledged that Jan. 1 is “commonly called New Year's Day” and Dec. 25 is “commonly called Christmas Day.” Thanksgiving, presumably, was identified by its name because its date changes from year to year.